The present invention relates to an end-face lapping apparatus and lapping method for lapping end faces of rod members such as fibers for optical communications.
Optical fibers are used by adhesive-fixing a fiber within the center bore of a ferrule as a principal member of a connector and then lapping smoothly a ferrule end face and a fiber end face at a same time into a mirror finish. If the lapped surfaces of the ferrule and the fiber are not normal to the center axis of the ferrule or the lapped surface has a mar, the oppositely-positioning accuracy in an optical connector connecting between opposite ferrules degrade, resulting in large loss. The lapped surface of the ferrule, including the optical fiber, therefore requires a lap finish with accuracy.
There is, for example, a disclosure in Japanese Laid-open Patent Publication No. H3-26456, as a conventional optical fiber end-face lapping apparatus. The optical fiber end-face lapping apparatus disclosed in this publication has an eccentric board that rotates on a concentric circle of a rotation disc and a planetary gear on the eccentric board to transmit the rotation of a revolution motor so that these are combined with a lapping board to cause the lapping board to rotate and revolve.
In the conventional optical fiber end-face lapping apparatus, however, the revolution mechanism uses the planetary gear. Accordingly, even when the revolution motor is stopped, if the rotation shaft is given rotation, the planetary gear rotates while being in mesh along with a revolution motor gear being stopped. As a result, the lapping board is put in a revolutional motion. Due to this, there has been a problem that a restriction arises in setting the r.p.m. for the rotation and revolution optimally for lapping conditions.
Also, the conventional optical fiber end-face lapping apparatus is arranged to attach a fixing jig board that fixes with a plurality of ferrules having an optical fiber received inside, oppositely in parallel to the lapping board on a support table, thereby securing finished end-face accuracy of lapped objects. However, errors in attaching them inevitably occur due to the machining accuracy in the support table and the fixing jig board. As a result, there has been a defect that the plurality of the ferrules fixed in the fixing jig board, i.e. fibers, are obliquely press-contacted with the lapping board. To this end, there is a problem that a finished surface is somewhat deviated from a convex spherical surface having a center as a vertex of an ideal optical fiber.
Under such situations, the present applicant has made an application to solve the above-stated problem. This application is PCT International Publication WO94/09944, wherein the end-face lapping apparatus described in this publication has a fixing jig board for fixing a plurality of ferrules fixed with an optical fiber to support this fixing jig board by a support mechanism, and a lapping board provided with a lapping member for lapping the ferrules oppositely to the ferrules. The plurality of the ferrules are abutted at their end faces against the lapping member to have a same pressing force acting thereon at all times. The lapping board is driven by a lapping motion mechanism that is capable of performing rotation and revolution independently to thereby working the end faces of the plurality of the ferrules into a convex spherical surface.
According to the conventional lapping, however, the lap path formed on the lapping member assumes an annular configuration as shown in FIG. 7, so that the lapping member is used merely at only one part thereof in lapping. Therefore, the cost of the lapping members as expendibles occupies the greater part of the total lapping cost. That is, if lapping is performing 3-6 times, the lap sheet as a lapping member worn away, requiring periodical replacement for lapping and raising the cost. On the other hand, where the lapping member is used for a long period of time, there is a problem that the efficiency of lapping lowers the lapping quality is deteriorated.
The present invention is to solve such problems, and it is the object to provide an end-face lapping apparatus and method of lapping that is improved in the efficiency of utilizing lapping members.
A first form of the present invention for solving the above-stated problems lies, in an end-face lapping apparatus, wherein a rod member is supported on an apparatus main body by a support mechanism through a fixing jig board, a lapping board having a lapping member for lapping the rod member being rotatably swingably supported on the apparatus main body by a drive mechanism, the drive mechanism causing the lapping board to rotate about a first rotating center and at the same time swivel about about a second rotating center to thereby carry out lapping while urging the rod member fitted in the fixing jig board against the lapping member of the rotatably swinging lapping board by the support mechanism, the end-face lapping apparatus characterized to have a relative position shift means for shifting the relative position of the lapping board and the fixing jig board, and the rod member being lapped at a different portion of the lapping member each time the relative position shift means shifts the relative position of the lapping board.
Here, the lapping member is relatively large with respect to the lap path due to swiveling simultaneous with rotation of the lapping member.
Also, the fixing jig board, for example, is arranged capable of placing a plurality of rod members at positions generally equally distant from a center thereof.
A second form of the present invention lies, in an end-face lapping method, wherein a rod member is supported on an apparatus main body by a support mechanism through a fixing jig board, a lapping board having a lapping member for lapping the rod member being rotatably swingably supported on the apparatus main body by a drive mechanism, the drive mechanism causing the lapping board to rotate about a first rotating center and at the same time swivel about about a second rotating center to thereby carry out lapping while urging the rod member fitted in the fixing jig board against the lapping member of the rotatably swinging lapping board by the support mechanism, the end-face lapping method characterized in that the lapping member is provided large with respect to the lap path due to the relative motion, and lapping being made at a different portion of the lapping member by shifting the relative position relative to the fixing jig board on each lap operation.